title: Somatic ATP1A1, ATP2B3, and KCNJ5 mutations in aldosterone-producing adenomas.
abstract: Aldosterone-producing adenomas (APAs) cause a sporadic form of primary aldosteronism and somatic mutations in the KCNJ5 gene, which encodes the G-protein-activated inward rectifier K(+) channel 4, GIRK4, account for ≈40% of APAs. Additional somatic APA mutations were identified recently in 2 other genes, ATP1A1 and ATP2B3, encoding Na(+)/K(+)-ATPase 1 and Ca(2+)-ATPase 3, respectively, at a combined prevalence of 6.8%. We have screened 112 APAs for mutations in known hotspots for genetic alterations associated with primary aldosteronism. Somatic mutations in ATP1A1, ATP2B3, and KCNJ5 were present in 6.3%, 0.9%, and 39.3% of APAs, respectively, and included 2 novel mutations (Na(+)/K(+)-ATPase p.Gly99Arg and GIRK4 p.Trp126Arg). CYP11B2 gene expression was higher in APAs harboring ATP1A1 and ATP2B3 mutations compared with those without these or KCNJ5 mutations. Overexpression of Na(+)/K(+)-ATPase p.Gly99Arg and GIRK4 p.Trp126Arg in HAC15 adrenal cells resulted in upregulation of CYP11B2 gene expression and its transcriptional regulator NR4A2. Structural modeling of the Na(+)/K(+)-ATPase showed that the Gly99Arg substitution most likely interferes with the gateway to the ion binding pocket. In vitro functional assays demonstrated that Gly99Arg displays severely impaired ATPase activity, a reduced apparent affinity for Na(+) activation of phosphorylation and K(+) inhibition of phosphorylation that indicate decreased Na(+) and K(+) binding, respectively. Moreover, whole cell patch-clamp studies established that overexpression of Na(+)/K(+)-ATPase Gly99Arg causes membrane voltage depolarization. In conclusion, somatic mutations are common in APAs that result in an increase in CYP11B2 gene expression and may account for the dysregulated aldosterone production in a subset of patients with sporadic primary aldosteronism.
authors.affiliation: Division of Internal Medicine and Hypertension, Department of Medical Sciences, University of Torino, Torino, Italy. tracyann.williams@unito.it.
authors.forename: Tracy Ann
authors.initials: TA
authors.lastname: Williams
authors.forename: Silvia
authors.initials: S
authors.lastname: Monticone
authors.forename: Vivien R
authors.initials: VR
authors.lastname: Schack
authors.forename: Julia
authors.initials: J
authors.lastname: Stindl
authors.forename: Jacopo
authors.initials: J
authors.lastname: Burrello
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Buffolo
authors.forename: Laura
authors.initials: L
authors.lastname: Annaratone
authors.forename: Isabella
authors.initials: I
authors.lastname: Castellano
authors.forename: Felix
authors.initials: F
authors.lastname: Beuschlein
authors.forename: Martin
authors.initials: M
authors.lastname: Reincke
authors.forename: Barbara
authors.initials: B
authors.lastname: Lucatello
authors.forename: Vanessa
authors.initials: V
authors.lastname: Ronconi
authors.forename: Francesco
authors.initials: F
authors.lastname: Fallo
authors.forename: Giampaolo
authors.initials: G
authors.lastname: Bernini
authors.forename: Mauro
authors.initials: M
authors.lastname: Maccario
authors.forename: Gilberta
authors.initials: G
authors.lastname: Giacchetti
authors.forename: Franco
authors.initials: F
authors.lastname: Veglio
authors.forename: Richard
authors.initials: R
authors.lastname: Warth
authors.forename: Bente
authors.initials: B
authors.lastname: Vilsen
authors.forename: Paolo
authors.initials: P
authors.lastname: Mulatero
mesh_terms: D000306:Adrenal Cortex Neoplasms / Q000150:complications / Q000235:genetics*; D018246:Adrenocortical Adenoma / Q000150:complications / Q000235:genetics*; D000328:Adult; D000450:Aldosterone / Q000096:biosynthesis* / Q000235:genetics; D019405:Cytochrome P-450 CYP11B2 / Q000235:genetics; D005260:Female; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels / Q000235:genetics*; D015870:Gene Expression; D006801:Humans; D006929:Hyperaldosteronism / Q000209:etiology / Q000235:genetics* / Q000378:metabolism; D006973:Hypertension / Q000209:etiology / Q000235:genetics / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009154:Mutation; D053499:Plasma Membrane Calcium-Transporting ATPases / Q000235:genetics*; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics*
chemical_list: D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; C484274:KCNJ5 protein, human; D000450:Aldosterone; D019405:Cytochrome P-450 CYP11B2; C499076:ATP1A1 protein, human; D053499:Plasma Membrane Calcium-Transporting ATPases; C506962:ATP2B3 protein, human; D000254:Sodium-Potassium-Exchanging ATPase
keywords: Conn adenoma; adrenal glands; aldosterone; hypertension; potassium channels; sodium-potassium–exchanging ATPase